title: Central motor conduction time.
abstract: Central motor conduction time (CMCT) is the time taken for neural impulses to travel through the central nervous system on their way to the target muscles. When the motor cortex is stimulated with transcranial magnetic stimulation (TMS), CMCT is calculated by subtracting the peripheral conduction time from the motor evoked potential latency elicited by motor cortical TMS. CMCT in infants and children reaches adult level at about age of 6 years for the lower limbs. The alterations of CMCT in various neurological conditions are reviewed in this chapter. Prolongation of CMCT occurs due to slowing of conduction through rapidly conducting corticospinal fibers, as seen in various disorders such as demyelinating diseases (multiple sclerosis, MS), amyotrophic lateral sclerosis, structural lesions in the corticospinal tract such as stroke and compressive myelopathy, and neurodegenerative disorders including multiple system atrophy and progressive supranuclear palsy. As CMCT is prolonged in certain clinical conditions, it is of diagnostic value in some neurological disorders such as myelopathy, amyotrophic lateral sclerosis, and MS when used together with other clinical and electrophysiological measures. It could also be used as a prognostic marker in some of neurological conditions, such as myelopathy and MS.
authors.affiliation: Division of Neurology, Department of Medicine, University of Toronto and Division of Brain Imaging & Behaviour Systems - Neuroscience, Toronto Western Research Institute, Toronto, Canada.
authors.forename: Kaviraja
authors.initials: K
authors.lastname: Udupa
authors.forename: Robert
authors.initials: R
authors.lastname: Chen
mesh_terms: D000818:Animals; D019054:Evoked Potentials, Motor / Q000502:physiology; D006801:Humans; D009044:Motor Cortex / Q000502:physiology*; D009431:Neural Conduction / Q000502:physiology*; D011930:Reaction Time / Q000502:physiology*; D050781:Transcranial Magnetic Stimulation
keywords: central motor conduction time (CMCT); diagnostic utilities of TMS; movement disorders; transcranial magnetic stimulation (TMS)